New perspectives on biology,disease progression,and therapy response of head and neck cancer gained from single cell RNA sequencing and spatial transcriptomics

Head and neck squamous cell carcinoma(HNSCC)is one of the most frequent cancers worldwide.The main risk factors are consumption of tobacco products and alcohol,as well as infection with human papilloma virus.Approved therapeutic options comprise surgery,radiation,chemotherapy,targeted therapy through epidermal growth factor receptor inhibition,and immunotherapy,but outcome has remained unsatisfactory due to recurrence rates of~50%and the frequent occurrence of second primaries.The availability of the human genome sequence at the beginning of the millennium heralded the omics era,in which rapid technological progress has advanced our knowledge of the molecular biology of malignant diseases,including HNSCC,at an unprecedented pace.Initially,microarray-based methods,followed by approaches based on next-generation sequencing,were applied to study the genetics,epigenetics,and gene expression patterns of bulk tumors.More recently,the advent of single-cell RNA sequencing(scRNAseq)and spatial transcriptomics methods has facilitated the investigation of the heterogeneity between and within different cell populations in the tumor microenvironment(e.g.,cancer cells,fibroblasts,immune cells,endothelial cells),led to the discovery of novel cell types,and advanced the discovery of cell-cell communication within tumors.This review provides an overview of scRNAseq,spatial transcriptomics,and the associated bioinformatics methods,and summarizes how their application has promoted our understanding of the emergence,composition,progression,and therapy responsiveness of,and intercellular signaling within,HNSCC.

Epidemiology and Histopathology of Cancers of the Upper Aerodigestive Tract in the ENT and Head and Neck Surgery Department of the Ignace Deen National Hospital

Introduction: Head and neck cancers represent a significant burden of cancer, collectively ranking fourth for cancer incidence and second for cancer mortality worldwide. Objective: To study the epidemiological and histopathological aspects of head and neck cancers in the ENT-CCF department of Ignace Deen National Hospital. Materials and Methods: This was a descriptive retrospective study covering a period of 5 years from September 1, 2016, to September 30, 2021. Results: We collected 43 cases of head and neck cancers, representing a hospital frequency of 1.85%. The mean age was 45.21 ± 13.23 years. Males predominated, accounting for 65.12%, compared to 34.88% for females, with a male-to-female ratio of 1.87. Housewives accounted for 27.90%, followed by farmers at 23.26% and traders/merchants at 18.60%, with 41.86% being uneducated. The main risk factors were tobacco (37.21%) and alcohol (34.88%). Pain (53.49%), dysphonia (51.16%), and dyspnea (39.53%) were the main presenting symptoms. Squamous cell carcinoma (74.42%) and large cell lymphoma (18.60%) were the most commonly cited histological types. Conclusion: Head and neck cancers remain relatively common in our country. Improving prognosis depends on early diagnosis of the condition, resuscitation resources, and prompt management.

Classificatory updates in verrucous and cuniculatum carcinomas:Insights from the 5^(th) edition of WHO-IARC head and neck tumor classification

The International Agency for Research on Cancer(IARC)and World Health Organization(WHO)collaboratively produce the'WHO Blue Books'essential tools standardizing the diagnostic process for human cancers.Regular updates in this classification accommodate emerging molecular discoveries,advances in immunohistochemical techniques,and evolving clinical insights.The 5th edition of the WHO/IARC classification of head and neck tumors refines the'Oral Cavity and Mobile Tongue'chapter,including sections for non-neoplastic lesions,epithelial tumors,and tumors of uncertain histogenesis.Notably,the epithelial tumors section is rearranged by tumor behavior,starting with benign squamous papillomas and progressing through potentially malignant oral disorders to oral squamous cell carcinoma(OSCC).The section on OSCC reflects recent information on epidemiology,pathogenesis,and histological prognostic factors.Noteworthy is the specific categorization of verrucous carcinoma(VC)and carcinoma cuniculatum(CC),both associated with the oral cavity and distinct in clinical and histologic characteristics.This classification adjustment emphasizes the oral cavity as their predominant site in the head and neck.Designating specific sections for VC and CC aims to provide comprehensive insights into these unique subtypes,elucidating their clinical features,distinct histological characteristics,prevalence,significance,and clinical relevance.By categorizing these subtypes into specific sections,the 5th edition of the WHO classification aims to provide a more nuanced and detailed account,enhancing our understanding of these specific variants within the broader spectrum of head and neck tumors.

Clinical treatment considerationsin the intensity-modulated radiotherapy era for patients with NO-category nasopharyngeal carcinoma and enlarged neck lymph nodes

Background:Nasopharyngeal carcinoma(NPC) shows a high proportion of lymph node metastasis,and treatment guidelines have been developed for positive nodes.However,no irradiation guidelines have been proposed for patients with enlarged neck lymph nodes(ENLNs) that do not meet the radiological criteria of 10 mm in diameter for positive lymph nodes.This study aimed to determine the prognostic value and radiation dose for ENLNs in NO-category NPC patients treated with intensity-modulated radiotherapy(IMRT).Methods:We reviewed the medical data of 251 patients with non-metastatic,NO-category NPC treated with IMRT.Receiver operating characteristic curves were used to calculate the cut-off value of the ENLN diameter for the prediction of disease failure.The biological equivalent dose(BED) for ENLNs was calculated.Patient survival was compared between the small and large ENLN groups.Independent prognostic factors were identified using the Cox proportional hazards model.Results:The estimated 4-year regional relapse-free survival rate was higher in patients with ENLNs ≥5.5 mm than in those with ENLNs <5.5 mm(100%vs.98.8%,P=0.049),whereas disease-free,overall,and distant metastasis-free survival rates were similar between the two groups.After adjusting for various factors,ENLN diameter was not identified as an independent prognostic factor(P > 0.05 for all survival rates).In the subgroup analysis,patients receiving BED ≥72 Gy had a similar prognosis as patients receiving BED <72 Gy in both the small and large ENLN groups.The multivariate analysis also confirmed that BED≥72 Gy was not associated with significantly improved prognosis in patients with NO-category NPC.Conclusions:A BED of 72 Gy to ENLNs is considerably sufficient to provide a clinical benefit to patients with NO-category NPC.Prospective studies are warranted to validate the findings in the present study.

Glasgow prognostic score after concurrent chemoradiotherapy is a prognostic factor in advanced head and neck cancer

Objective: This study aims to evaluate the impact and potential prognostic roles of the pre- and post-treatment Glasgow prognostic score (GPS) and the change thereof in patients with advanced head and neck cancer undergoing concurrent chemoradiotherapy (CCRT). Methods: We collected GPS and clinicopathological data of 139 stage III, IVA, and IVB head and neck cancer patients who underwent CCRT between 2008 and 2011. Their GPSs pre- and post-CCRT and the change thereof were analyzed for correlations with recurrence and survival. Results: The GPS changed in 72 (51.8%) patients, with worse scores observed post-CCRT in 65 (90.3%) of the GPS changed patients. Patients in the improved GPS group showed a tendency toward better survival. From the multivariate analysis, the post-CCRT GPS level was an independent prognostic factor in addition to tumor stage. Conclusions: After CCRT, a high GPS was revealed to be an important predictor of survival for advanced head and neck cancer.

The Department of Otolaryngology Head and Neck Surgery,PLA General Hospital (national key academic unit) The PLA Institute of Otolaryngology (PLA key laboratory for acoustic trauma) The PLA Medical College Department of Deafness Education Key Laboratory

Led by four generations of leadership from late Prof.JIANG Sichang(academician,Chinese Academy of Engineering),Prof.YANG Weiyan(Honorary President,Division of Otolaryngology Head and Neck Surgery,Chinese Medical Association),Prof.HAN Dongyi(President Elected,Division of Otolaryngology Head and Neck Surgery,Chinese Medical Association)to now Prof.YANG Shiming(President,Division of Otolaryngologists,

Summarizing the evidence for robotic-assisted bladder neck reconstruction: Systematic review of patency and incontinence outcomes

Objective:Bladder neck contracture and vesicourethral anastomotic stenosis are difficult to manage endoscopically,and open repair is associated with high rates of incontinence.In recent years,there have been increasing reports of robotic-assisted bladder neck reconstruction in the literature.However,existing studies are small,heterogeneous case series.The objective of this study was to perform a systematic review of robotic-assisted bladder neck reconstruction to better evaluate patency and incontinence outcomes.Methods:We performed a systematic review of PubMed from first available date to May 2023 for all studies evaluating robotic-assisted reconstructive surgery of the bladder neck in adult men.Articles in non-English,author replies,editorials,pediatric-based studies,and reviews were excluded.Outcomes of interest were patency and incontinence rates,which were pooled when appropriate.Results:After identifying 158 articles on initial search,we included only ten studies that fit all aforementioned criteria for robotic-assisted bladder neck reconstruction.All were case series published from March 2018 to March 2022 ranging from six to 32 men,with the median follow-up of 5e23 months.A total of 119 patients were included in our analysis.A variety of etiologies and surgical techniques were described.Patency rates ranged from 50%to 100%,and pooled patency was 80%(95/119).De novo incontinence rates ranged from 0%to 33%,and pooled incontinence was 17%(8/47).Our findings were limited by small sample sizes,relatively short follow-ups,and heterogeneity between studies.

Anesthetic Management of Neck Trauma with Traumatized Airway: A Case Report and Review

Neck trauma with a traumatized airway can be challenging for airway management, as the neck is a vital structure. Case Report: We are reporting on a 33-year-old male worker who suffered an industrial accident. A steel cord severely hit his neck. He was brought to our ER immediately. Upon arrival, he was conscious with stable vital signs. A physical examination revealed that his Adam’s apple was penetrated, and the adjacent soft tissue and structures were visible. A CT scan showed an anterior and left lateral neck penetrating injury with an open wound, exposure of the thyroid cartilage, a left thyroid cartilage fracture, and pneumoderma. He was urgently taken to the operating theater for airway stabilization and underwent six hours of exploration of the laryngopharyngeal cavity and closure of the laryngopharyngeal defect. He was then sent to the ICU. After two months in the hospital, he regularly follows up in the outpatient department. Conclusion: Effective decision-making for neck trauma with a compromised airway is crucial to ensure the patient’s safety.

MAD2L2 overexpression attenuates the effects of TNF-α-induced migration and invasion capabilities in colorectal cancer cells

Background:Colorectal cancer is a major global health concern,exacerbated by tumor necrosis factor-alpha(TNF-α)and its role in inflammation,with the effects of Mitotic Arrest Deficient 2 Like 2(MAD2L2)in this context still unclear.Methods:The colorectal carcinoma cell lines HCT116 and SW620 were exposed to TNF-αfor a period of 24 h to instigate an inflammatory response.Subsequent assessments were conducted to measure the expression of inflammatory cytokines,the activity within the p38 mitogen-activated protein kinase(p38 MAPK)and Phosphoinositide 3-Kinase/AKT Serine/Threonine Kinase pathway(PI3K/AKT)signaling cascades.Transcriptome sequencing and subsequent integrative analysis with the Cancer Genome Atlas(TCGA)program database revealed a significant downregulation of the key factor MAD2L2.Enhancement of MAD2L2 expression was facilitated via lentiviral vector-mediated transfection.The influence of this overexpression on TNF-α-prompted inflammation,intracellular signaling pathways,and the migratory and invasive behaviors of the colorectal cancer cells was then scrutinized.Results:TNF-αtreatment significantly increased the expression of Interleukin-1 beta(IL-1β)and Interleukin-6(IL-6),activated the MAPK p38 and PI3K/AKT signaling pathways,and enhanced cell migration and invasion.A decrease in MAD2L2 expression was observed following TNF-αtreatment.However,overexpression of MAD2L2 reversed the effects of TNF-α,reducing IL-1βand IL-6 levels,attenuating PI3K/AKT pathway activation,and inhibiting cell migration and invasion.Conclusions:Overexpression of MAD2L2 attenuates the pro-inflammatory effects of TNF-α,suggesting that MAD2L2 plays a protective role against TNF-α-induced migration and invasion of colorectal carcinoma cells.Therefore,MAD2L2 holds potential as a therapeutic target in the treatment of colorectal cancer.

Effect of Wearing a Maxillofacial Prosthesis on Masticatory Rhythm Improvement in Mandibulectomy Patients

Background: Recording jaw movement rhythms in patients with jaw defects is challenging using conventional tracking devices. However, masticatory rhythm is crucial for masticatory performance and nutritional intake. This study aimed to explore the impact of using a maxillofacial prosthesis to restore masticatory rhythm in mandibulectomy patients with a novel wearable device. Methods: Twelve patients who underwent mandibulectomy and were rehabilitated with maxillofacial prosthesis were recruited. Chewing rate, cycle durations, coefficient of variation of cycle durations (CV), changing times of skin morphology on the back of the ear pinna area (SM), and masticatory performance were measured during gum chewing without and with a denture using a wearable jaw movement rhythm tracking device. A paired t-test and the Pearson correlation coefficient were used for statistical analysis. Results: The chewing rate increased by 8.6 cycles/min with dentures (P P = 0.01). The CV and SM decreased with dentures (P = 0.004 and P = 0.01, respectively). Significant correlations were found between the CV and SM without dentures (P = 0.004). Conclusion: 1. Wearing maxillofacial prostheses can improve masticatory rhythm in patients who undergo mandibulectomy with Eichner B2 occlusal supports. 2. The wearable device is available for measuring masticatory rhythm in patients with jaw defects in clinics. 3. Changing times of the skin morphology on the back of the ear pinna indicate jaw movement stability through a simpler process than the coefficient of variation of cycle durations.

Engineering The Neck Hinge Reshapes The Processive Movement of Kinesin-3

Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.

Fibroblast activation protein (FAP) as a prognostic biomarker in multiple tumors and its therapeutic potential in head and neck squamous cell carcinoma

Background:Fibroblast activation protein(FAP),a cell surface serine protease,plays roles in tumor invasion and immune regulation.However,there is currently no pan-cancer analysis of FAP.Objective:We aimed to assess the pan-cancer expression profile of FAP,its molecular function,and its potential role in head and neck squamous cell carcinoma(HNSC).Methods:We analyzed gene expression,survival status,immune infiltration,and molecular functional pathways of FAP in The Cancer Genome Atlas(TCGA)and Genotype Tissue Expression(GTEx)tumors.Furthermore,to elucidate the role of FAP in HNSC,we performed proliferation,migration,and invasion assays post-FAP overexpression or knock-down.Results:FAP expression was elevated in nine tumor types and was associated with poor survival in eight of them.In the context of immune infiltration,FAP expression negatively correlated with CD8+T-cell infiltration infive tumor types and positively with regulatory T-cell infiltration in four tumor types.Our enrichment analysis highlighted FAP’s involvement in the PI3K-Akt signaling pathway.In HNSC cells,FAP overexpression activated the PI3K-Akt pathway,promoting tumor proliferation,migration,and invasion.Conversely,FAP knockdown showed inhibitory effects.Conclusion:Our study unveils the association of FAP with poor tumor prognosis across multiple cancers and highlights its potential as a therapeutic target in HNSC.

PPP1R14A is Associated with Immunotherapy Resistance in Head and Neck Squamous Cell Carcinoma Identified by Single-Cell and Bulk RNA-Sequencing

Objective To identify nivolumab resistance-related genes in patients with head and neck squamous cell carcinoma(HNSCC)using single-cell and bulk RNA-sequencing data.Methods The single-cell and bulk RNA-sequencing data downloaded from the Gene Expression Omnibus database were analyzed to screen out differentially expressed genes(DEGs)between nivolumab resistant and nivolumab sensitive patients using R software.The Least Absolute Shrinkage Selection Operator(LASSO)regression and Recursive Feature Elimination(RFE)algorithm were performed to identify key genes associated with nivolumab resistance.Functional enrichment of DEGs was analyzed with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses.The relationships of key genes with immune cell infiltration,differentation trajectory,dynamic gene expression profiles,and ligand-receptor interaction were explored.Results We found 83 DEGs.They were mainly enriched in T-cell differentiation,PD-1 and PD-L1 checkpoint,and T-cell receptor pathways.Among six key genes identified using machine learning algorithms,only PPP1R14A gene was differentially expressed between the nivolumab resistant and nivolumab sensitive groups both before and after immunotherapy(P<0.05).The high PPP1R14A gene expression group had lower immune score(P<0.01),higher expression of immunosuppressive factors(such as PDCD1,CTLA4,and PDCD1LG2)(r>0,P<0.05),lower differentiation of infiltrated immune cells(P<0.05),and a higher degree of interaction between HLA and CD4(P<0.05).Conclusions PPP1R14A gene is closely associated with resistance to nivolumab in HNSCC patients.Therefore,PPP1R14A may be a target to ameliorate nivolumab resistance of HNSCC patients.

Paclitaxel for second-line treatment of squamous cell carcinoma of the head and neck:A multicenter retrospective Italian study

BACKGROUND Squamous cell carcinoma of the head and neck(SCCHN)accounts for 3%of all malignant tumors in Italy.Immune checkpoint inhibitors combined with chemotherapy is first-line treatment for SCCHN;however,second-line treatment options are limited.Taxanes are widely used for combination therapy of SCCHN,as clinical trials have shown their efficacy in patients with this disease,partic ularly in patients with prior therapy.AIM To perform a multicenter retrospective study on the efficacy and safety of weekly paclitaxel for SCCHN.METHODS All patients were previously treated with at least one systemic therapy regimen,which included platinum-based therapy in the vast majority.No patient received prior immunotherapy.RESULTS Median progression-free survival(mPFS)was 3.4 months and median overall survival(mOS)was 6.5 months.Subgroup analysis was performed according to three principal prognostic factors:Smoking,alcohol consumption,and body mass index.Analysis demonstrated reduced survival,both mOS and mPFS,in the unfavorable prognostic groups,with the biggest deltas observed in mOS.CONCLUSION Weekly paclitaxel provided favorable survival and disease control rates,with low severe adverse events.Paclitaxel is a safe and valid therapeutic option for patients with SCCHN who received prior therapy.

Nanomaterials for refining tumor microenvironment and enhancing therapy in head and neck squamous cell carcinoma: a review

Head and neck squamous cell carcinoma (HNSCC) is a prevalent and lethal solid tumor with a high mortality rate. Conventional cancertreatments, including surgery, radiotherapy, and chemotherapy, primarily target cancer cell eradication. However, uncontrolled proliferation and metabolic activities of these cells result in abnormalities in nutrient levels, hypoxia, and immunosuppression within the tumor microenvironment (TME). These factors constrain the efficacy of traditional treatments by promoting drug resistance, recurrence, and metastasis. Nanomaterials (NMs), such as nanozymes, can exhibit enzymatic activity similar to that of natural enzymes and offer a promising avenuefor the direct modification of the TME through catalytic oxidation-reduction processes. Moreover, they can serve as sensitizers or drug deliverycarriers, enhancing the efficacy of traditional treatment methods. Recently, NMs have garnered significant attention from oncologists. Thisreview begins with an overview of the composition and unique characteristics of the TME. Subsequently, we comprehensively exploredthe application of NMs in the treatment of HNSCC. Finally, we discuss the potential prospects and challenges associated with usingNMs in biomedical research.

Finite Element Analysis of Coronal Shear Fractures of the Femoral Neck: Displacement of the Femoral Head and Effect of Osteosynthetic Implants

Coronal shear fractures of the femoral neck (CSFF) are the most challenging to treat among proximal femur fractures, directly affecting the life expectancy of patients with osteoporosis. However, an adequate osteosynthesis method has not been elucidated yet. This study investigated the displacement direction of the femoral head fragment and its effect on the bone using finite element method. A finite element model for CSFF was developed from CT image data of a patient with osteoporosis using Mechanical Finder (ver. 11). Subsequently, finite element analyses were performed on six osteosynthesis models under maximum load applied during walking. The compressive stresses, tensile stresses, and compressive strains of each model were examined. The results suggested that the compressive and tensile stress distributions were concentrated on the anterior side of the femoral neck. Compressive strain distribution in the femoral head and neck was concentrated in four areas: at the tip of the blade or lag screw, the anteroinferior side of the blade or lag screw near the fracture site, and the upper right and lower left near the junction of the blade or lag screw and nail. Thus, the distribution of both these stresses revealed that the femoral head fragment was prone to anterior and inferior displacement. Distribution of compressive strains revealed the direction of the stress exerted by the osteosynthetic implant on the bone. The same results were observed in all osteosynthetic implants;thus, the findings could lay the foundation for developing methods for placing osteosynthetic implants less prone to displacement and the osteosynthetic implants themselves. In particular, the study provides insight into the optimal treatment of CSFF.

mad-overexpression down regulates the malignant growth and p53 mediated apoptosis in human hepatocellular carcinoma BEL-7404 cells

Mad protein has been shown as an antagonist of cMyc protein in some cell lines. The effect of Mad protein to the malignant phenotype of human hepatoma BEL7404 cell line was investigated experimentally. An eukarryotic vector pCDNA Ⅲ containing full ORF fragmentof mad cDNA was transfected into targeted cells. Under G418 selection, stable Mad-overexpressed cells were cloned.Studies on the effect of Mad over-expression in cell proliferation and cell cycle revealed that cell morphology of the Mad-overexpressed BEL-7404-M1 cells was significantly different from the parent and control vector transfected cells. DNA synthesis, cell proliferation and anchorage-independent growth in soft-agar of the madtransfected cel1s were partially inhibited in comparison to control cells.Flow Cytometry analysis indicated that mad over-expression might block more transfectant cells at G0/G1 phase, resulting in the retardation of cell proliferation. RT-PCR detected a marked inhibition of the expression of cdc25A, an important regulator gene of G0/G1to S phase in cell cycle. It was also found that Mad protein overexpression could greatly suppress p53-mediated apoptosis in BEL-7404-M1 cells in the absence of serume.Thus, Mad proteins may function as a negative regulator antagonizing c-Myc activity in the control of cell growth and apoptosis in human hepatocellular carcinoma BEL7404 cells.madoverexpression and regulation of cell growth and apoptosis

Targeting head and neck tumoral stem cells： From biologicalaspects to therapeutic perspectives

Head and neck squamous cell cancer(HNSCC) is the sixth most common cancer in the world. Effective therapeutic modalities such as surgery, radiation, chemotherapy and combinations of each are used in the management of the disease. In most cases, treatment fails to obtain total cancer cure. In recent years, it appears that one of the key determinants of treatment failure may be the presence of cancer stem cells(CSCs) that escape currently available therapies. CSCs form a small portion of the total tumor burden but may play a disproportionately important role in determining outcomes. CSCs have stem features such as self-renewal, high migration capacity, drug resistance, high proliferation abilities. A large body of evidence points to the fact that CSCs are particularly resistant to radiotherapy and chemotherapy. In HNSCC, CSCs have been increasingly shown to have an integral role in tumor initiation, disease progression, metastasis and treatment resistance. In the light of such observations, the present review summarizes biological characteristics of CSCs in HNSCC, outlines targeted strategies for the successful eradication of CSCs in HNSCC including targeting the self-renewal controlling pathways, blocking epithelial mesenchymal transition, niche targeting, immunotherapy approaches and highlights the need to better understand CSCs biology for new treatments modalities.

Benign neck masses showing restricted diffusion: Is there a histological basis for discordant behavior?

Diffusion weighted imaging(DWI) evolved as a complementary tool to morphologic imaging by offering additional functional information about lesions. Although the technique utilizes movement of water molecules to characterize biological tissues in terms of their cellularity, there are other factors related to the histological constitution of lesions which can have a significant bearing on DWI. Benign lesions with atypical histology including presence of lymphoid stroma, inherently increased cellularity or abundant extracellular collagen can impede movement of water molecules similar to malignant tissues and thereby, show restricted diffusion. Knowledge of these atypical entities while interpreting DWI in clinical practice can avoid potential misdiagnosis. This review aims to present an imaging spectrum of such benign neck masses which, owing to their distinct histology, can show discordant behavior on DWI.

NECK LEAF 1, a GATA type transcription factor, modulates organogenesis by regulating the expression of multiple regulatory genes during reproductive development in rice

In the monocot rice species Oryza sativa L., one of the most striking morphological processes during reproductive development is the concurrence of panicle development with the sequential elongation of upper internodes （UPIs）. To elucidate the underlying molecular mechanisms, we cloned the rice gene NECK LEAF 1 （NL1）, which when mutated results in delays in flowering time, smaller panicles with overgrown bracts and abnormal UPI elongation patterns. The NL1 gene encodes a GATA-type transcription factor with a single zinc finger domain, and its transcripts are de- tected predominantly in the bract primordia, which normally degenerate in the wild-type plants. Overexpression of NL1 in transgenic plants often gives rise to severe growth retardation, less vegetative phytomers and smaller leaves, suggesting that NL1 plays an important role in organ differentiation. A novel mutant allele of PLASTOCHRON1 （PLAD, a gene known to play a key role in regulating leaf initiation, was identified in this study. Genetic analysis demonstrated an interaction between nil and plal, with NL1 acting upstream of PLA1. The expression level and spatial pattern of PLA1 were found to be altered in the nil mutant. Furthermore, the expression of two regulators of flowering, Hd3a and OsMADS1, was also affected in the nil mutant. On the basis of these findings, we propose that NL1 is an intrinsic factor that modulates and coordinates organogenesis through regulating the expression of PLA1 and other regulatory genes during reproductive development in rice.